Sonic transducer



March 28,1967 J. F. CAIN somo TRANSDUCER Filed NOV. 27, 1963 INVENTOR JOHN f'.- C'//V mwmw.

United States Patent O 3,311,712 SONIC TRANSDUCER John F. Cain, Pacific Palisades, Calif., assigner, by direct and mesne assignments, of one-half to Alan A. Allen, Los Angeles, Calif., and one-half to Harry Z. Marx, La Jolla, Calif.

Filed Nov. 27, 1963, Ser. No. 326,595 6 Claims. (Cl. 179-113) This invention relates to a transducer device and has for an object to reproduce sound by contact between a resonant component of the device and any suitable solid body, such as a Wall, ceiling, oor, plaque, or board of wood, metal or other such common materials.

Heretofore, it was common to cause the vibrations of an electro-magnetic reproducer to induce vibration in a speaker, such as a diaphragm or cone. The present transducer is complete in itself as an operating and commercial device, requiring only to be aixed to a body, as above, to cause the latter to reproduce sounds throughout the audio-frequency range, as instituted by electro-magnetic fluctuations of one or more electric reproducers.

Another object of the invention is to provide a sonic transducer, as above characterized, that produces a compound acoustical circuit in the resonant component thereof, thereby reproducing high quality sound of fully adequate volume in a body of material as above mentioned, and which is not necessarily provided for acoustical effects, as are loudspeakers, for instance.

A further object of the invention is to provide a sonic transducer provided with a resonator that, by mere point impingernent against a solid body of ordinary elasticity, as wood, metal or plastic, or a body of elasticity of lesser degree, as cement, stone and the like, causes such body to produce omnidirectional sound, enabling application of the transducer in hidden or out-of-the-way places, such as closets, behind walls, and in attics.

A still further object of the invention is to provide a device, as above characterized, that may be used as a single unit affording the desired audio frequency range, or comprising two units, preferably in side-by-side arrangement, one having a low frequency range and the other a high frequency range.

This invention also has for its objects to provide s-uch means that are positive in operation, convenient in use, easily installed in working position and easily disconnected therefrom, economical of manufact-ure, relatively simple, and of general 'superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description, and which is based on the accompanying drawing. However, said drawing merely shows and the following description merely describes, preferred embodiments of the present invention, which are given Iby way of illustration or example only.

In the drawing, like reference characters designate similar parts in the several views.

FIG. l is a side elevational View `of sonic transducer according to the present invention, with its mounting housing in vertical section, and shown in operative position.

FIG. 2 is a front elevational View of said transducer, the housing in this view also being in vertical section.

FIG. 3 is a plan view of said transducer as seen on the plane of line 3-3 of FIG. 2.

PIG. 4 is `an enlarged front view of a resonator used in the invention, `and shown in a flexed condition, as when responding to the vibrations due to the electromagnetic fluctuations of the transducers armature.

The present transducer may comprise a single soundreproducing unit and may be effectively use-d as such.

3,31 L? i2 Patented Mar. 2S, 1967 ICC The transducer that is illustrated comprises two reproducer units 5 and 5a, the former to reproduce sounds in the higher or treble range and the latter to reproduce sounds in the lower or bass range, thereby providing reproduction of sound throughout the entire audio frequency range. In practice, the illustrated contiguous side-by-side arrangement of the units is preferred.

Whether one or two units, or even more than two, are provided, the same are mounted in a housing or carrier 6 which is provided with a mounting bracket 7. FIGS. l and 2 show a solid body 8 with which the present device is operatively associated and to which the bracket '7 is affixed. While, as shown, the device is mounted on the member 8, it may .be mounted independently thereof, providing the present unit has the desired operative position in relation to member 3, as will become clear hereinafter.

The unit 5 (as well as the unit 5a) comprises, conventionally, a held-generating magnet 9, an electro-magnetic exciter coil l0 disposed in the field of said magnet, and an armature 11 extending through said coil. This wellknown combination operates by means of electrical pulses, regardless of their origin, sent to the coil to create an electro-magnetic field that circulates in the pole pieces 12 of the magnet to excite the armature 11, causing the same to vibrate or move accordingly.

The unit 5 (as well as the unit 5a), according to the present invention, comprises, generally, a fulcrum 13 for the armature 11i, a built-in air gap llito impart predetermined timbre or pitch to the sound reproduced by the device, damper means i5 to eect control of movement of the armature during excitation thereof, and a resonator 16 preferably carried by the end of the armature reanote from the damper means 35.5. An alternative construction may provide the resonator on an extension of the armature beyond the means 1S.

The armature fulcrum 13 comprises non-magnetic pivot members 17, one on each side of the armature and provided with knife-edge ends that impinge on the armature, thereby allowing the same to move, in limited degree, on the fulcrum provided. Said members 17 are so placed that the armature is movable between the poles 18 of the pole pieces 12. FIG. 2 shows how the armature 1i extends through the coil 1t? with the fulcrum 13 at one end of the coil and the armature end 19 extending through the other end between the poles i8. A comparison of the units 5 and 5a, as in FIGS. 2 and 3, will show that the air gap 14 of the unit 5 is greater than that of the unit 5a. The smaller the air gap, the higher pitched will be the sound reproduced by the device. Hence, in the drawing, the unit S represents the woofer or low frequency sound reproducer, and the unit 5a represents the tweeter or high frequency sound reproducer.

The damper means 1S is shown as two resilient pads 2i), usually rubber, on 'both sides of the armature end 19 to dampen the movement of said end, as mentioned. Said pads may be held in clips 2i that may be adjusted to change the pad compression, as desired, and/ or to create equal compression on the pads for centering of the armature between them. Said clips and the pads 2i) may be covered by a pad-retaining strip 22 and the assembly held in place -by suitable screws 23 that enter the poles 1S.

In the present construction, the pole piece plates 12 are secured together in stacked arrangement, with the magnets 9, by screws 24 at opposite ends of the device. This arrangement provides for holding the armature 11 (or both armatures if units 5 and 5a are used) tightly in place between the knife-edges of the pivot members 17. Said members 17 are shown as fixed to the plates 12 by screws 2S.

The resonator le comprises a non-magnetic, metallic shank or post 26 that extends longitudinally from the armature end that is remote from the damper means 15. An enlarged flange Z7 is integrally provided on said shank about midway of its length. The length and diametral size of the shank may vary. Proportionally, it is related to the size, thickness and general mass of the armature and it is preferred that the proportion of the shank to the armature be such that the inertia effects on the armature be minimized. Hence, the size and mass of the flange 27 may vary to vary inertia effects and, thereby, vary tone qualities of the resonator.

A resonator amplifier 28 is shown as a flared end on the shank 26 to provide additional mass to said shank. On the outer extremity of the flange 27 and on the side thereof vertically beneath one of the poles 18, is provided a thin member having a high modulus of elasticity. In this case, the same comprises a steel needle 29 which is used as a probe to impinge on a surface of the solid body 8, in the manner shown. Said needle probe has its point on the axis of the shank 26, the amplifier 28 `being moved, in part, to provide clearance for the needle in its sloping disposition from the flange 27 to its point.

The housing or carrier 6 serves as a holder for the above-described units or 5a, slots 30 in said holder enabling vertical adjustment of said units, as desired. The carrier or holder is preferably non-magnetic.

The bracket 7 preferably comprises any suitable memlber of limited resilience for mounting the carrier 6, preferably on the body 8 but, in any case, on a fixed support so `associated with the body 8 as to afford the desired operative relationship of the transducer to said body 8. A screw 31 is shown for securing the bracket 7 in place.

When mounting the present transducer, as described, the units 5 and 5a are shifted in the carrier 6 to bring the needle points into a desired degree of impingement with the surface 8a of said body 8. Screws 32 are then tightened, and the device is in operative position, the bracket 7 flexing as conditions warrant.

As the armature Il vibrates in response to changes in the magnetic flux that is exciting the armature, the resonator has a pendulum-like movement that causes flexure of the needle 29 in one direction, as in FIG. 4, and in the opposite direction, as the magnetic circuit changes according to the character of the electrical impulses sent to the coil or coils which, if two coils are used, are preferably connected in parallel electrically. Since the gap 33 between the needle and the resonator amplifier 28 varies as the armature vibrates, the resonator creates a primary acoustical circuit directly through the flexed needle 29, and also a secondary acoustical circuit from the shank 26 to the needle. The vibrations of the needle are amplified in the body 8, are of normal audibility, and are quite faithful to the electrical input of the transducer.

It is desirable that liners of cushioning material '34 be interposed between the carrier 6 and the transducer units.

While the foregoing has illustrated and described what is now contemplated to be the best mode of carrying out the invention, the constructions are, of course, subject to modification without departing from the spirit and scope of the invention. Therefore, it is not desired to restrict the invention to the particular forms of construction illustrated and described, but to cover all modifications that may fall within the scope of the appended claims.

Having thus described the invention, what is claimed and desired to ybe secured by Letters Patent is:

1. A sonic transducer comprising:

(a) an electro-magnetic reproducer having an exciter coil,

(b) an armature extending through said coil and mounted on a pivot to move pivotally in response to variations in the electrical impulses induced in the coil,

(c) a resonator carried by one vibrating end of the armature,

(d) said resonator including a flexible and elongated pointed. member,

(e) the point of the member being adapted to be impinged upon the surface of a fixed and solid member to flex and transmit its. vibrations to said solid member and, thereby, produce sound, and

(f) flexible means for fixedly mounting the reproducer.

2. A sonic transducer according to claim 1 provided with vibration-damping means to control armature move- 10 ment.

3. A sonic transducer comprising:

(a) an electro-magnetic reproducer having an exciter coil,

(b) an armature extending through said ooil and mounted on a pivot to move pivotally in response to variations in the electrical impulses induced in the coil,

(c) a resonator carried by one vibrating end of the armature,

(d) said resonator including a flexible and elongated pointed member,

(e) the point of the member fbeing adapted to be impinged upon the surface of a fixed and solid member to flex and transmit its vibrations to said solid member and, thereby, produce sound,

(f) a carrier for the transducer,

(g) means for adjustably mounting the transducer on the carrier, and

(h) flexible means for flxedly mounting the carrier.

4. In a sonic transducer having an electro-magnetic unit adapted to be resiliently mounted upon .a solid member and provided with an exciter coil, a bar armature extending through said coil, the improvements comprising:

(a) a pivot for said armature on which the same vibratorily moves in response to excitation by the coil,

(b) a resonator carried by an end of the armature and including a flexible needle having a point adapted to be impinged upon the surface of said solid member to flex and transmit its vibrations to said solid member and, thereby, reproduce sound,

(c) the opposite end of the armature extending through and beyond the exciter coil, and

(d) means resiliently engaged with said opposite end to dampen the armature vibrations.

5. In a sonic transducer having an electro-magnetic unit `adapted to be resiliently mounted upon a solid member and provided with an exciter coil, a bar armature extending through said coil, the improvements comprising:

(a) a pivot for said armature on which the same vibratorily moves in response to excitation by the coil,

(b) a resonator carried by an end of the armature and including a flexible needle having a point adapted to be impinged upon the surface of said solid member to flex and transmit its vibrations to said solid member and, thereby, reproduce sound,

(c) said electro-magnetic unit being provided with spaced magnet poles beyond the end of the exciter coil that is opposite to the end having the resonator,

(d) the armature having an end extending in an opposite direction through and beyond said coil, and

(e) means resilently engaged with said opposite end to dampen the yarmature vibrations.

6. In a sonic transducer according to claim 5, the resilient means comprising compressible pads engaged with opposite faces of the last-mentioned armature ends.

References Cited by the Examiner UNITED STATES PATENTS KATHLEEN H. CLAFFY, Primary Examiner.

A. MCGILL, Assistant Examiner. 

1. A SONIC TRANSDUCER COMPRISING: (A) AN ELECTRO-MAGNETIC REPRODUCER HAVING AN EXCITER COIL, (B) AN ARMATURE EXTENDING THROUGH SAID COIL AND MOUNTED ON A PIVOT TO MOVE PIVOTALLY IN RESPONSE TO VARIATIONS IN THE ELECTRICAL IMPULSES INDUCED IN THE COIL, (C) A RESONATOR CARRIED BY ONE VIBRATION END OF THE ARMATURE, (D) SAID RESONATOR INCLUDING A FLEXIBLE AND ELONGATED POINTED MEMBER, (E) THE POINT OF THE MEMBER BEING ADAPTED TO BE IMPINGED UPON THE SURFACE OF A FIXED AND SOLID MEMBER TO FLEX AND TRANSMIT ITS VIBRATIONS TO SAID SOLID MEMBER AND, THEREBY, PRODUCE SOUND, AND (F) FLEXIBLE MEANS FOR FIXEDLY MOUNTING THE REPRODUCER. 